The present invention relates to an electronic balance capable of correcting an error in the measured value, the error being due to the turning moment caused by a load being placed deviatedly from a required point of placement, such as the center of the pan.
In general, when a load is placed deviatedly from a required point of placement, such as the center of the pan, which will be hereinafter referred to as "eccentrically placed", the turning moment M exterts on the pan, thereby producing an error E in the measured value. An adjustment will be required for the geometrical precision of the Roberval mechanism of the balance. If the Roberval balance has a sufficiently rigid construction to receive a load without any strain, the relations between the turning moment M and the possible error E will become linear. FIG. 1 (I) shows every possible situation of the relations therebetween, in which the lines A and B show opposite extreme situations. A skilled operator could produce an optimum situation S within an allowable range .delta.. However, this requires a high degree of skill and experience. For example, when a Roberval balance has a precision of 1/10.sup.6 to 1/2.times.10.sup.6, the adjustment must be made in the range of 0.1 to 0.05.mu.. On the contrary, if the Roberval balance does not have a sufficiently rigid construction, and receives a load with some degree of strain, the relations between the turning moment M and the possible error E cannot be linear but vary as shown in FIG. 1 (II), which shows every possible situation of the relations therebetween. Curves C and D show opposite extreme situations between which all possibilities can exist. However, in this case the most skilled operator could not produce an optimum situation T within an allowance range .delta..sub.2. FIG. 1 (II) is a characteristic graph for an extremely high precision balance, and the allowable range .delta..sub.2 is strict enough to admit of no negligence.